Field of the Invention
The invention concerns a filter holder for receiving filter cassettes having two plates which are movable relative to each other on at least one rail and between which the filter cassettes can be clamped, wherein a first plate is arranged so as to be fixed and a second, parallel plate is arranged so as to be movable, with a predefinable clamping pressure, by means of a drive. The invention further concerns a method for sterilizing a filter holder in an autoclave, with filter cassettes which are clamped between two plates that are movable relative to each other on at least one rail, wherein for sterilizing, the second movable plate is clamped against the first plate, which is fixedly connected to the rail, with a predefined tension rod pressure, by means of at least one tension rod arranged parallel to the rail and having a spring tensioning element, and the filter holder is autoclaved in the autoclave.
Description of the Related Art
The “SARTOFLOW®10 Stainless Steel Holder” company brochure discloses a filter holder for receiving filter cassettes with two plates that are movable relative to each other on parallel rails. The filter cassettes can be clamped between the plates. In this case, a first plate is fixedly arranged, and a second, parallel plate is arranged so as to be movable by means of a hydraulic drive with a predefinable clamping pressure. The hydraulic drive is designed as a hydraulic cylinder, which is arranged on a third plate fixedly connected to the rails. The hydraulic drive has a movable piston that moves the second movable plate in the direction of the first plate with a predefinable clamping pressure.
By using a hydraulic drive, the second plate can be moved with a high degree of precision and thus the predefined clamping force for moving the second plate, and thus the clamping pressure on the filter cassettes, can be precisely defined.
The disadvantage of such a basically tried and tested filter holder is that the filter holder cannot be autoclaved with the filter cassettes clamped in place. Because of the hydraulic fluid of the hydraulic drive, undesirable expansion would take place in the hydraulic cylinder, which would result in high clamping pressures or forces.
DE 37 08 733 C2 discloses a filter holder for receiving filter cassettes and has two plates movable relative to each other on a rail. The filter cassettes can be clamped between the plates. Here, a first plate and a second, parallel plate are movably arranged. Parallel to the rail, a tension rod having a spring tensioning element is provided by means of which rod the two plates can be connected to each other and clamped against the filter cassettes with a predefined tension rod pressure. The plates with the filter cassettes arranged in between them are manually joined together with a threaded connection by means of the tension rod. For the filtration process, the spring tensioning elements are blocked, and the clamping pressure with which the movable plate is pulled in the direction of the fixed plate is set manually by means of a torque wrench. To decrease the clamping pressure, the blocking of the spring tensioning element is cancelled by rotating the tension rod so that during the hot steam sterilizing process equalization can take place via the spring tensioning element. In this case, the advantage of hot steam sterilizing is offset by a certain lack of precision in the adjustment of the clamping pressure during the filtration process.
An object of the present invention is to improve the known filter holders such that, on the one hand, the pressure for clamping the plates with the filter cassettes arranged between them is adjustable with a high degree of precision by means of a drive while, on the other hand, the filter holder can be autoclaved with the filter cassettes clamped in place.
Another object is to provide a corresponding process for sterilizing the filter holders with filter cassettes.